International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B5. Istanbul 2004 
-f) in image space coordinate system and then transformed into 
total station coordinate system, we can get following equation: 
X; cosa 0 -sinafl 0 0 A 
Y, [=] 0 1 0 {0 cos£ -snA|r, 
Z; sina 0 cosa lo sing cos |Z | 
cosa 0 -sina |l 0 o Y Xx. x 
=; 0 | 0 0 cosf -sinfil Ys |* AE rm 
sinz 0 cosa |O sing cosB \ Zs, -f 
(1) 
where XiYn Zr coordinates of a object point in total 
station coordinate system 
ap --- horizontal angle and vertical angle of total 
station 
As > Yo > Zw Pas 0: Ko 777 Offset between 
camera and total station 
Considering coordinates of object point in ground coordinate 
system can be represented by the following equation: 
Y AA 
Ya {= (2) 
La Zr Lai 
where X Gi» Y. Gi? Zc: are coordinates of total station in 
ground coordinate et we can get: 
xX,-#; | [esa 0 -smaÿr © 0 x. x 
Ya Ya =] 0 1 0 0 cos —sinfl|F. mrAR. 
ZZ. sina 0 cose |O sing :cosf Zs, -f 
r= x 
. . f 
cosa -sinasinf#  -sinacos x 
0 cos —sin £ BE R AR, 
sina cosasnf#  cosacos P 1| Z., 
  
A 4 41x. d. d À a, a; x 
=18 8 BY +48 8 8, A 
6 6, 012, Cy C6, ee ff 
(3) 
Simplifying the equations (3), on addition of interior 
orientation elements xo,yo (the coordinates of the image 
principal point), we can get collinear equation in PTSS as 
following] 
LIXG A A, tA. + AZ, )- 
m; -Y,)-(G,X, + BY *BZ. )]+ 
mlZa-Za) € Xs, * OY, zu] 
  
  
BR E qas X AX, A. C AZ, 
mA; Ya) X, EX, ISP 4) 
nM Ae X GEH GA) 
LIQG X5) Xs, AY, AZ p 
mI(, -Y,)- (X, * BY, € BZ, ) 
cis Mn, GE $6 Z3] 
rT 
LIX — X56) (4 Xs, +41, + 4,25 N+ 
m. - Y5)-(X,, tB +B,25,)1+ 
AG -Z5:)- (X, -CK *GZ.)] 
where: A;, Bi. Ci, bomen, (i= 1, 2, 3) are coefficients; 
Xo, Yo----position of image principal point. 
2.5 Orientation Offset Calibration 
As described above, because of the rigid connection between 
camera and total station, position and pose of camera (exterior 
orientation parameters) can be derived by the position and 
orientation of total station and the orientation offset between 
camera and total station. Position and orientation of total station 
can be easily calculated with observations of total station in 
traversing. So at this time, to get the position and pose of camera 
(exterior orientation parameters), the calibration of orientation 
offset between camera and total station become necessary, 
which is normally divided into three steps: (1) Control bar 
(board) has been putted not far from (less than 5 meters) 
traverse point and object space coordinates of control points on 
calibration bar (board) are measured by use of total station. (2) 
Photos are taken at each traversing point and image coordinates 
of control points are (semi-) automatically extracted. (3) 
Calibration is implemented by use of bundle adjustment. 
From description above, it can be easily seen that PTSS just 
uses some “near control” for “far measurement” to avoid 
locating sufficient control points around or on the surface of 
measured objects and in this case true non-contact measurement 
becomes possible. The accuracy of this kind of control method 
will be described in next section. 
When calibrating through bundle adjustment, it is necessary to 
linearize Equation (4) for practical operation. After linearization 
of Equation (4), we obtain general form of error equations as 
following: 
vy, 2 a, AK, a AYsy au AZs t 01, 0, + 
a, AD, +a, AK, +5, AX, HO AY +B AZ, ~1 
Vy = ay AX 50 +a, Ag +a Ag, +a, Ap, + 
A A@, + ay AK, +0 AX, +b AY, +b, AZ 1, 
where a; (i =} j= 12,50) and b; (i = 12; = 1.2.33 
are coefficients derived from linearization and the derivation 
process is omitted here because of the limitation of space for 
this paper. 
Based on these error equations, normal equations can be formed 
through conventional methods. The solution of normal 
equations would give the elements of orientation offset between 
camera and total station. And subsequently exterior orientation 
parameters of each image can be determined. 
Once the offset ( À se Youll Z soif Doi 6 Oy Ky) is 
calibrated, according to our test, it is normally unchanged 
during the whole measurement session. 
(5) 
3 MEASUREMENT PROCESS AND MODE 
The whole process of digital terrestrial photogrammetry 
includes two stages: ficld survey and indoor photogrammetric 
processing. Field survey mainly focuses on data acquisition. 
Firstly, traversing is complemented through total station and 
object coordinates of necessary control points are measured and 
photos are taken by metric digital camera. For specific 
measurement mission, three different measurement modes can 
be used depending upon the measurement condition and 
requirement: (1) Photos are captured completely by PTSS; (2) 
Photos are captured partly by handheld camera and partly by 
PTSS and in this case the photos captured by PTSS, named 
control photos, server as control in whole calculation process; (3) 
All photos are captured by handheld camera and total station is 
just used to obtain object coordinates of control or check points. 
Thus the measurement process can be very flexible. 
    
    
      
   
        
     
   
   
    
   
  
  
  
  
   
  
   
   
  
   
  
    
    
     
  
  
  
   
     
   
   
   
  
   
   
   
   
   
   
   
  
   
  
  
   
  
  
    
    
   
   
   
   
   
  
    
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